The characteristics of a breast cancer -- including hormone-receptor status and HER2 status -- can change over time. These changes may happen because the cancer cells change themselves or because treatment changes the cells. A cancer's characteristics are used to decide which treatments will offer the most benefit.
In the study reviewed here, researchers found that 12.1% of metastatic breast cancers that were biopsied had different characteristics than the original cancer that was diagnosed in the breast. All the cancers were metastatic because they had spread from the breast area to the liver. These results were presented at the 2010 American Society of Clinical Oncology (ASCO) annual meeting.
Right now, doctors don't biopsy every metastatic breast cancer that is diagnosed. In many cases, the characteristics of the metastatic cancer are the same as the original breast cancer. Still, this research suggests that in some cases a cancer's characteristics can change if the cancer comes back in another place in the body. So doing a biopsy on metastatic cancer may make sense in some cases, especially for breast cancer that has spread to the liver.
In this study, the researchers looked at biopsy results from 255 women who had been diagnosed with breast cancer and then later diagnosed with metastatic breast cancer in the liver. They compared the biopsy results from the original breast cancer to the biopsy results from the metastatic breast cancer in the liver. If a cancer characteristic was different in the metastatic biopsy compared to the original biopsy, it was called discordant. Discordant characteristics meant that the cancer cells had changed over time.
Overall, 13.9% of the cancers had a change in HER2 status:
Overall, 14.5% of the cancers had a change in hormone-receptor status:
A biopsy on breast cancer that has spread to the liver usually can be done easily and safely. This study suggests that the information from a metastatic cancer biopsy could help doctors make more informed treatment decisions based on the most up-to-date cancer characteristics. Based on this and other studies, many doctors feel that when breast cancer spreads to soft tissue such as the liver, another biopsy should be done on the metastatic cancer, provided it's safe to do so. Information from the metastatic biopsy can help make sure that treatment decisions are based on the actual cancer characteristics.
Breast cancer that has spread to the bones (as opposed to soft tissue such as the liver) is harder to biopsy. Still, an earlier study by the same researchers found that metastatic cancer had the same characteristics as the original cancer about 95% of the time. This suggests that breast cancer that has spread to bones is less likely to change its characteristics over time so probably doesn't have to be biopsied.
If you've been diagnosed with metastatic breast cancer, especially breast cancer that has spread to soft tissue such as the liver, you may want to talk to your doctor about this study and ask if doing a biopsy on the metastatic cancer makes sense.
You can learn more about breast cancer characteristics on the Breastcancer.org Your Pathology Report pages.
CHICAGO (MedPage Today) -- Biopsy of distant metastases may identify a change in tumor biology in a proportion of breast cancer patients, according to a retrospective study.
The estrogen, progesterone, or HER2 receptor status of liver metastases differed from that of the primary breast tumor in a way that altered endocrine therapy or targeted agent treatment in 12.1% of patients, Giuseppe Curigliano, MD, PhD, of the European Institute of Oncology in Milan, and colleagues found.
"When safe and easy to perform, a biopsy of the metastatic lesion should be considered in all patients, particularly when there is a long interval from the first diagnosis, since it is likely to impact treatment choice," they reported here at the American Society of Clinical Oncology meeting.
Although the study examined only liver metastases, the results likely generalize, agreed Eric P. Winer, MD, of the Dana-Farber Cancer Institute in Boston, who moderated the press conference at which the results were presented.
"The default position in a woman with metastatic breast cancer should be to perform a biopsy, it's really not performing a biopsy that should be an exception," Winer said.
Rebiopsy is usually a low morbidity procedure, added William J. Gradishar, MD, of Northwestern University in Chicago, in explaining why he and a growing number of other oncologists have started to rebiopsy women who were originally diagnosed a year or more before the discovery of metastases.
"We have had in the last few years a number of series that raised the issue of rebiopsy, and this [study] falls in line with those," he said in an interview. "There's certainly a trend moving back to rebiopsy."
However, bone metastases may be an exception.
Not only are these more difficult to assess for hormone and HER2 receptor status, but as Curigliano noted based on a prior study from his group, "We found a very high percentage of concordance between the primary and the bone mets, at least 95%."
For the current study, Curigliano and colleagues analyzed a database of 1,250 ultrasound-guided liver biopsies performed from 1995 to 2008. The database included 255 consecutive patients with matched primary and liver tissue samples assessed for ER, PR, and HER2 status.
For HER, 13.9% of the matched primary breast and liver metastasis samples were discordant.
Notably, 31.5% of those that would have been considered candidates for trastuzumab (Herceptin) therapy because of a positive primary actually had negative receptor status on the metastasis biopsy. Of those initially negative for HER2, 5.9% of metastases were positive for HER2.
For ER status, 14.5% of tumors were discordant between primary and secondary tumors in these women's matched tumor samples -- 25.9% of those with a negative primary had a positive secondary and 11.2% of those with a positive primary had a negative liver metastasis.
The reason for the results may be that exposing the tumor to a prolonged period of treatment in one pathway may upregulate other pathways and make a difference in what cells survive to travel out into distant locations, Curigliano suggested.
He noted that breaking down the results by tumor characteristics showed that more endocrine resistance in tumors was associated with tendency to overexpress the HER2 pathway, "so this is the proof that we have some changes in the biology of tumor."
But he couldn't discount that inaccuracy of testing -- largely due to interobserver discordance in reading the percentage of cells that stain positive for the receptors -- could be playing a role as well.
All the biopsy assessments were carried out at the same center but by different pathologists, he said.
The researchers reported no conflicts of interest.
Winer reported conflicts of interest with Genentech.
Gradishar reported no conflicts of interest.
Primary source: American Society of Clinical Oncology Source reference: Locatelli MA, et al "Should liver metastases of breast cancer be biopsied to improve treatment choice?" ASCO 2010; Abstract CRA 1008.
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